HEATER GP-JACKET WATER 3845289 - Caterpillar

Load Control Valve (LOWER or DUMP Position)
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(12) Check valve (13) Spool (14) Piston (G) Port from the head end of the lift cylinder or of the tilt cylinder (H) Port from the lowering control valve or from the pilot valve for DUMP (J) Port from the lift control valve for RAISE or for TILT BACK (BB) Trapped oil (CC) Return oil (DD) Pilot oil (EE) Moving partsWhen the operator lowers the implement or the operator dumps the implement, pilot oil from the pilot valve flows to port (H). Pilot pressure acts on piston (14). Piston (14) shifts to the right in order to cause spool (13) to shift to the right. Spool (13) unseats from check valve (12). The bank valve directs high pressure oil to the rod end of the lift cylinder or to the rod end of the tilt cylinder. Oil from the head end of the lift cylinder or from the head end of the tilt cylinder flows in port (G), through the passage, and to port (J) .When the Operation and Maintenance Manual, SEBU7891, "Equipment Lowering with Engine Stopped" is performed, the operator uses the lowering control valve (4) in order to pressurize port (H) on the load control valves (3) for the lift cylinders with oil.Load Control Valve (Hydraulic Pressure Spike)
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(7) Relief valve (12) Check valve (13) Spool (14) Piston (G) Port from the head end of the lift cylinder or of the tilt cylinder (J) Port from the lift control valve for RAISE or for TILT BACK (AA) High pressure oil (FF) First pressure reduction (GG) Second pressure reduction (BB) Trapped oil (EE) Moving partsWhen the implement bumps into an object, a hydraulic pressure spike can result. In the case of a hydraulic pressure spike, the load control valve provides a relief in the hydraulic line. The increased pressure at port (G) opens relief valve (7). The pressure acts on piston (14). Piston (14) shifts to the right in order to cause spool (13) to shift to the right. Spool (13) unseats from check valve (12). The high pressure oil at port (G) flows through the passage and to port (J) .Load Control Valve (Engine Failure or Hose Failure)
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(12) Check valve (13) Spool (G) Port from the head end of the lift cylinder or of the tilt cylinder (H) Port from the lowering control valve or from the pilot valve for DUMP (J) Port from the lift control valve for RAISE or for TILT BACK (BB) Trapped oil (CC) Return oil (HH) Hydraulic void (EE) Moving partsIf the engine fails, oil from port (J) will drain to the tank. If a hose bursts, oil from port (J) will be open to the atmosphere. In both cases, pressure at port (G) will be higher than pressure at port (J). The pressure at port (G) will not be sufficient to open relief valve (7). Unless pilot pressure is directed to port (H), the spool (13) will not unseat from the check